Michael Niedermayer:
> No benchmark because this is not used in any speed relevant pathes nor is it
> used where __builtin_add_overflow is available.
> So I do not know how to realistically benchmark it.
>
> Signed-off-by: Michael Niedermayer <mich...@niedermayer.cc>
> ---
> libavutil/common.h | 9 ++++-----
> 1 file changed, 4 insertions(+), 5 deletions(-)
>
> diff --git a/libavutil/common.h b/libavutil/common.h
> index 92b721a59c..a48c0648f8 100644
> --- a/libavutil/common.h
> +++ b/libavutil/common.h
> @@ -303,11 +303,10 @@ static av_always_inline int64_t av_sat_add64_c(int64_t
> a, int64_t b) {
> int64_t tmp;
> return !__builtin_add_overflow(a, b, &tmp) ? tmp : (tmp < 0 ? INT64_MAX
> : INT64_MIN);
> #else
> - if (b >= 0 && a >= INT64_MAX - b)
> - return INT64_MAX;
> - if (b <= 0 && a <= INT64_MIN - b)
> - return INT64_MIN;
> - return a + b;
> + int64_t s = a+(uint64_t)b;
> + if ((int64_t)(a^b | ~s^b) >= 0)
> + return b < 0 ? INT64_MIN : INT64_MAX;
> + return s;
> #endif
> }
>
>
Returning INT64_MAX ^ (b >> 63) would have even less branches
(untested). See https://godbolt.org/z/oYadG3
- Andreas
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